This invention relates to locking dogs and Kelly bar adapters which are used to drivingly connect the shaft of an earth anchor to a Kelly bar.
When utility poles are erected, they are often provided with guy wires to stabilize the poles. The guy wires are connected, at their bottom ends, to earth anchors which have been driven into the ground. Typically, the earth anchor is operatively connected to a Kelly bar, which in turn is driven by an hydraulic motor. The motor turns the Kelly bar and earth anchor to drive the anchor into the ground. After the anchor is driven into the ground, the Kelly bar is disconnected from the earth anchor shaft.
In the past, the lack of standardization by utility truck manufacturers on Kelly bar sizes, as well as multiple uses of the installing vehicles and tools, led designers to offer a Kelly bar adapter with a bolted flange so that one Kelly bar could be used with multiple tools. However, many different Kelly bar adapters had to be developed for the variations in Kelly bar sizes and types. The use of the flanged adapter also enabled the use of mechanical in-line torque indicators. Earth anchors are driven into the ground under a desired amount of torque. Obviously, the application of too much torque to the earth anchor and its shaft can damage the shaft. The in-line torque indicator allowed the torque applied to the earth anchor to be controlled, so that it would not exceed a certain desired amount. A common assembly for driving an earth anchor A into the ground is shown in FIG. 1. A locking dog D is fixed to the top of the wrench tube W which surrounds the earth anchor's shaft S. The locking dog D has a plate on its top, and an in-line torque indicator T is bolted to the locking dog plate. A Kelly bar adapter B having a bottom plate is bolted to the top of the torque indicator T, and a Kelly bar K is received in the Kelly bar adapter B. Thus the rotation of the Kelly bar K is transmitted to the anchor A by way of the Kelly bar adapter B, the in-line torque indicator T, and the locking dog D.
Over the years, Kelly bar sizes have been standardized, reducing the need for adapters. However, bolted connections, such as shown in FIG. 1, between the Kelly bar adapter B, the torque indicator T, and drive adapter or locking dog D continued to be used. This has continued, even though the use of the bolted connections create problems. The bolted connections reduce the strength and integrity of the Kelly bar/drive shaft connection, a connection which is highly stressed and requires properly installed high grade-bolts to make a reliable connection. Further, field personnel often do not have access to sufficient quantities of high-grade bolts, and are forced to use weaker bolts. Additionally, the torque indicators are difficult and time consuming to install, and thus are rarely used. When not used, the earth anchor can be improperly driven into the ground. Lastly, the cost of field labor and the high expenses of maintaining the installing vehicles made it expensive to assemble, disassemble, and maintain the various tools needed for an anchor installation.